1. Field of the Invention
The invention relates to the field of printing systems, and in particular, to processing JDF job tickets in a printing system to identify printing parameters that define how to print files.
2. Discussion of Related Art
Printing systems generally include a localized print controller that connects to one or more host systems. The print controller controls the overall operation of the printing system including, for example, host interfacing, interpretation or rendering, and lower level process control or interface features of the print engines of the printing system. Host interaction may include appropriate adapters for coupling the printing system to one or more host systems that transmit printable files to the printing system. The printable files are generally encoded in the form of a page description language (PDL), such as PostScript (PS), PDF, PCL, PPML, etc.
In whatever form the printable files may be encoded or formatted, the print controller within the printing system interprets or renders the file to generate sheetside bitmaps of the file. For example, the printable file may include page descriptions for each page of the file that are written in a particular PDL. The print controller may then interpret the page descriptions for each page to generate the sheetside bitmaps for the file. The sheetside bitmaps represent the images to be printed on one side of a sheet of paper by a print engine. The print controller stores or buffers the sheetside bitmaps in accordance with storage capabilities of the particular print controller. The print controller then forwards the sheetside bitmaps to one or more print engines (also referred to as an imaging engine or as a marking engine). The print engine then performs an imaging process to mark the printable medium (e.g., a sheet of paper) with the sheetside bitmaps provided by the print controller. The print engine may comprise a laser print engine, an ink-jet print engine, or another type of imaging system that transfers each sheetside bitmap to corresponding pixels on paper.
In present printing systems, when the host system is instructed to print a particular file comprised of textual and graphical content, the host system converts the file into a printable file in one of a variety of PDLs. The host system also prepends printing parameters (also referred to as device control commands or instructions) to the printable file. For example, if the printable file is defined in PostScript, then an application running on the host system will access the Postscript Printer Description (PPD) file for the printer. The PPD file describes the fonts, paper sizes, resolution, and other capabilities that are standard for a particular Postscript printer. Based on the PPD file, a user selects one or more printing parameters for printing the printable file, such as n-up, 2-sided printing, etc, and the printing parameters are prepended to the PostScript file. The host system then transmits the PostScript file along with the printing parameters to the printing system, such as over a network. The print controller within the printing system then processes the printing parameters prepended to the PostScript file to identify how the printable file should be processed within the printing system.
One way of describing the printing parameters for a print job is through Job Definition Format (JDF). JDF is a standard for defining a print job, such as indicating one or more printable files for a print job, and defining printing parameters for printing these files. A JDF message is in XML format and describes a job ticket, a message description, and message interchange. A JDF message includes information that enables a device to determine what files are needed as input (if any), where the files are located, and what processes the device should perform. In present printing systems, processing of JDF messages, and more particularly JDF job tickets, is performed in the host system. In response to receiving or identifying a JDF job ticket, the host system processes the JDF job ticket to identify the printing parameters for a print job. The host system then generates a printable file in the appropriate PDL that includes the content intended for printing, and prepends the printing parameters to the printable file. This can cause problems as it may overload the host system in processing the JDF job ticket and generating the printable files, as the printable files and the prepended printing parameters can get quite large. Also, if a network connection is used between the host system and the printing system, then the large printable files may congest the network or unnecessarily use up network resources.